If the band is sufficiently narrow, then talking about marginal tax rates becomes largely a red herring. To take the extreme example, it is possible to imagine a 200 % marginal tax in a band precisely one € wide (I know that this example is ridiculous, but I hope it illustrates the point). The bandwidth is needed if you want to make an apples-to-apples comparison across borders (along with much else, as noted upthread).

- Jake

Friends come and go. Enemies accumulate.